Question 1

The term used to describe all of the chemical reactions within a cell is:

Accepted Answer

Metabolism is the term used to describe all of the chemical reactions within a cell, including both anabolic and catabolic reactions, as well as other processes such as energy conversion and chemical signaling. Choices A, B, and E only refer to specific subsets of these reactions. Choice C refers specifically to the addition of phosphate groups to molecules, which is a common process within metabolism but does not encompass all of the reactions involved.

Question 2

_____ reactions are anabolic reactions involving ligases for synthesis and the release of one water molecule for each bond formed.

Accepted Answer

The description matches the condensation reaction, which involves the synthesis of a larger molecule by removing a water molecule for each bond formed. Ligases are also enzymes that catalyze condensation reactions. Reduction involves the gain of electrons, oxidation involves the loss of electrons, and transfer involves the movement of a molecule or group from one molecule to another.

Question 3

Formation of peptide bonds between amino acids to build a polypeptide would be called

Accepted Answer

Peptide bond formation involves building larger molecules from smaller ones, which is the process of anabolism. Phosphorylation involves the addition of a phosphate group to a molecule, fermentation is the process of breaking down organic compounds to produce energy, catabolism is the breakdown of molecules into smaller parts, and glycolysis is the breakdown of glucose into pyruvate in the cytoplasm.

Question 4

Enzymes that catalyze the removal of electrons from one substrate and the addition of electrons to another are called

Accepted Answer

Oxidoreductases are enzymes that catalyze oxidation-reduction reactions, where electrons are transferred from one substrate to another. They are also referred to as dehydrogenases or reductases. Choice A, transferases, are enzymes that transfer functional groups from one substrate to another. Choice C, lyases, are enzymes that catalyze the cleavage of chemical bonds without the use of water or oxidation-reduction reactions. Choice D, isomerases, are enzymes that catalyze the rearrangement of bonds within a molecule, leading to the formation of an isomer. Choice E, ligases, are enzymes that catalyze the formation of chemical bonds using ATP or a similar molecule.

Question 5

The most likely place where an exoenzyme participates in a chemical reaction is

Accepted Answer

Exoenzymes are enzymes that are secreted by a cell and function outside of that cell, hence the most likely place they participate in a chemical reaction is outside of the cell.

Question 6

A holoenzyme is a combination of a protein and one or more substances called

Accepted Answer

A holoenzyme is composed of both a protein (the apoenzyme) and a non-protein component (the cofactor) that is necessary for its activity. Therefore, choice D, cofactors, is the correct answer. Choices A, B, C, and E are incorrect because they do not accurately describe the non-protein component of a holoenzyme.

Question 7

Each of the following are true of enzymes except

Accepted Answer

Enzymes decrease the activation energy required for a reaction to occur, rather than increasing it.

Question 8

Enzymes that function inside a cell are

Accepted Answer

Endoenzymes are enzymes that function inside the cell, while exoenzymes are secreted outside of the cell. Apoenzymes are inactive forms of enzymes that require a cofactor to function. Constitutive enzymes are continuously produced by the cell, while regulated enzymes are only produced in response to specific stimuli.

Question 9

Enzymes that are only produced when substrate is present are termed

Accepted Answer

Enzymes that are only produced when substrate is present are called induced enzymes. This means that their production is induced or triggered by the presence of their specific substrate. Exoenzymes and endoenzymes refer to the location where the enzyme works (outside or inside the cell), while constitutive enzymes are constantly produced regardless of the presence of a substrate. Conjugated enzymes refer to enzymes that are bound to other molecules, such as cofactors or prosthetic groups.

Question 10

Important components of coenzymes are

Accepted Answer

Coenzymes are organic compounds that are necessary for enzyme function, providing a transfer site for a functioning catalyst. These organic molecules cannot function without assistance, which is where coenzymes come in. Vitamins are the most common type of coenzyme, and they are often the components that allow enzymes to function. Vitamins can act as a source of energy, regulate metabolism or facilitate chemical reactions, they are the most important components of coenzymes in most metabolic reactions.

Question 11

Reactants are converted to products by

Accepted Answer

Chemical reactions involve the breaking and forming of bonds between atoms in reactant molecules to create new product molecules. Enzymes can facilitate this process by lowering the activation energy required for the reaction to occur, but they do not release or bind to the reactants themselves to convert them to products.

Question 12

Ribozymes are

Accepted Answer

Ribozymes are RNA molecules that can catalyze reactions, and are known to be involved in RNA splicing. They are not the same as ribosomes, which are large molecular complexes involved in protein synthesis. Ribozymes are found in both prokaryotes and eukaryotes. They are not directly involved in DNA splicing.

Question 13

Enzymes are

Accepted Answer

Enzymes are proteins that function as catalysts in a variety of biological reactions. They speed up the rate of reactions without being used up or broken down in the process.

Question 14

Enzymes that catalyze the removal of a a functional group and its subsequent attachment to a new substrate are called:

Accepted Answer

Transferases are enzymes that catalyze the transfer of a functional group from one molecule (the donor) to another (the acceptor).

Question 15

A type of cofactor would be

Accepted Answer

The answer of A type of cofactor would be
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Question 16

The bacterial genus Bacillus can utilize starch as a nutrient by splitting the starch molecule into smaller molecules of glucose,with the addition of water.The enzymes to do this would be classified as:

Accepted Answer

Hydrolases are enzymes that break down substances by adding water to the chemical bond. In this case, the enzyme is breaking down starch into glucose by adding water to the bond between the glucose molecules, making it a type of hydrolase.

Question 17

The cell's metabolic reactions involve the participation of _____ that lower the activation energy needed for the initiation of a reaction.

Accepted Answer

Enzymes lower the activation energy required to initiate a metabolic reaction.

Question 18

An apoenzyme is

Accepted Answer

An apoenzyme is the protein part of a holoenzyme, which is an enzyme made up of both protein and non-protein components. The apoenzyme itself is not active and requires the binding of a cofactor or coenzyme to become functional.

Question 19

Your bacterium is growing on a type of medium called casein agar,which contains milk protein (casein).There is a clear zone around the growth area of the bacterium,showing that it is synthesizing the enzymes needed to catalyze the breakdown of casein.These enzymes are considered:

Accepted Answer

The clear zone around the growth area of the bacterium indicates that it is secreting enzymes that break down casein, which are exoenzymes. Apoenzymes are inactive without a cofactor, ribozymes are RNA molecules that catalyze reactions, regulated enzymes are controlled by signals from the cell, and endoenzymes catalyze reactions within the cell itself. None of these descriptions fit the situation described in the question.

Question 20

All of the following are exoenzymes except

Accepted Answer

ATP synthase is an intracellular enzyme involved in the production of ATP within the cell. Exoenzymes are enzymes that are secreted outside of the cell to break down larger molecules in the surrounding environment. Streptokinase, penicillinase, collagenase, and elastase are all examples of exoenzymes.

Quiz 8: Microbial Metabolism: the Chemical Crossroads of Life